Defects in craniofacial development to cleft palate and/or cleft lip in more than 1 out of 1,000 births. Investigation of the molecular mechanisms of craniofacial development will lead to improved diagnosis, treatment, and prevention of these birth defects. The long term objective of this project is to understand the role of the transcription factor Zfhep in craniofacial development. Targeted disruption of the Zfhep/deltaEF-1 gene in mice created cleft secondary palate, hypertrophy of Meckel's cartilage, and perinatal death. However, it is unknown whether these facial defects are due to a direct, or indirect involvement of Zfhep in development. Defining the temporal-spacial expression of Zfhep is an essential step towards determining whether it has a direct role in craniofacial development. The specific goals of this project are to determine the expression pattern of both Zfhep-1 and Zfhep-2 in the mesenchyme and epithelium of the palate, and in Meckel's cartilage during mouse development using both in situ hybridization and immunohistochemistry. We will also investigate the expression of Zfhep during development of tooth buds. We will determine the specific cell types (pre-chrondrocytes, chrondrocytes, or hypertrophy chrondrocytes) expressing Zfhep during development of Meckel's cartilage. The results of this R03 application will provide a complete picture of the temporal and spatial expression pattern of Zfhep during craniofacial development, and demonstrate where Zfhep can have direct effects on development. Subsequent work will investigate the molecular mechanism(s) of Zfhep action during craniofacial development.